Good, with potential, but it can be better.
First of all, you've got a good idea to work with. The dialogues were really funny and the fight scene was good enough, even the one where Mario takes out the bazooka. However, I feel that the beginning is a bit slow. I lost ethusiasm right there, but then the fight scene perks it up. Perhaps some other sound effects or some spoken dialogue might help the first part.
Finally, the ending seems inconclusive. Maybe next time you could add a hint of what Bowser's gonna do with the princess, ya know. Save a good joke for the end. Anyway, I see a lot of potential in your animation and the story, you just gotta keep the timeline "moving". Congrats, and keep at it!